Packaging system and method for packaging objects

ABSTRACT

There is provided a system for packaging objects on a conveyor using a tubular plastic film. More specifically, the invention provides a system, wherein the tubular plastic film can be wrapped around the objects in a horizontal manner.

FIELD OF THE INVENTION

The invention relates to a system and method for continuously packaging multiple objects on a conveyor using a tubular plastic film. More specifically, the invention provides a system, wherein the tubular plastic film can be wrapped around long objects.

BACKGROUND OF THE INVENTION

It is already known to package objects, including compressible objects, by completely or partially manual operations, wherein the objects are introduced into a pre-manufactured, bag-shaped plastics film, i.e. a bag, prior to packaging. In some cases the bag-shaped plastics films can be advanced automatically to the operator from a stack; and likewise the objects may be advanced to the site of packaging by means of belt conveyors etc. Manual operations are cost-intensive and likewise the capacity-even that of automatic auxiliary equipment-is limited. The latter means that the execution of the operations becomes very space-intensive. The manual handling of the bags can be replaced by an automated handling only with difficulty since it is difficult to detect corners, rims and edges accurately to enable accurate seizure of the bags. Unless the bags are seized accurately there is a risk of them being damaged during the handling procedure.

Stretch packaging aims to give protection to a stack of goods during transport against humidity and other environmental influences. The wrapping with a foil hood ensures stability to the packed goods.

Prior art systems are generally used for the purposes of wrapping up a product, which is arranged for the most part on a pallet, at least in part with a tubular film in a packaging machine. This serves to stabilize the product and to provide protection against the surroundings. The tubular film may be configured as a hood that is closed at the top or as a band that is open at the top and the bottom.

Prior art systems utilize a tubular film portion matching the size of the product and the systems basically unroll a portion of the film onto gathering fingers which are fastened to a frame. A gathering drive unit is then moved into contact with the tubular film portion such that an operative connection is created. By driving the gathering roller, the tubular film portion is gathered-up onto the individual gathering fingers such that a film store laid in folds is formed on the respective gathering finger. Once the tubular film portion has been gathered-up, the gathering fingers are driven in a substantially horizontal manner such that the tubular film portion is expanded or stretched. Expanding or stretching refers to a state where an elastic or elastic-plastic deforming of the tubular film occurs. The gathering fingers are then driven in a vertical manner along the product. At the same time the tubular film is released from the gathering fingers and the product is wrapped up therein as a result of the elastic resiliency of the tubular film portion.

Such systems are used for example in hood packaging installations. These may be installations which operate on the basis of what is known as the hood stretching process or the hood shrinking process. Both processes are distinguished by the fact that a portion of a tubular film is pulled or pushed over any desired cargo, or that the cargo is introduced into the portion of tubular film by means of a lifting table. This is referred to hereafter as wrapping of cargo.

In the case of most hood packaging installations, the portion of tubular film is first reefed by means of a reefing device, to then be slipped over the cargo by the reefing device or by a separate drawing-over device and thereby unreefed. During the reefing, a supply of portions of tubular film laid in folds, which is also referred to hereafter as a film store, is formed at the bottom of the reefing fingers. If the reefing device is also used for the drawing over, the reefing device is moved in relation to the cargo, possibly after stretching the portion of tubular film. During this relative movement, the portion of tubular film is pulled off from the reefing fingers, is also referred to as unreefed.

U.S. Pat. No. 5,024,042 discloses a system for packaging objects in hose-shaped foil which comprises a movable packaging frame having a plurality of horizontally arranged gripping arms for holding and stretching the foil, a conveyor for supporting objects and transporting it towards the packaging frame, so that the object is delivered between the gripping arms. US502402 does not disclose gripping arms equipped with opposing and activated rollers and that a second conveyor is positioned next to the packaging frame, where the second conveyor transports the packaged object away from the packaging frame.

EP0652156 discloses a machine for packaging a number of food casing strands in film, which is tubular and made of plastics. The packaging method comprises that the film is transferred to transport means while forming a number of wrinkle shaped folds. The film positioned on the transport means is then cut off from the remaining part of the film, following which the open ended tubular film is stretched and arranged to receive the food casing strands. The objects are then transferred into the stretched tubular plastic film in such a manner that the film is gradually pulled off because the diameter of the group of food casing strands is larger than the diameter of the open end in the tubular film. Finally the opposite end of the tubular film package with the food casings strands is closed.

U.S. Pat. No. 3,798,872 discloses an apparatus for manually stuffing foodstuff into tubular netting. The apparatus comprises an immobile stuffing tubular element, a slideable blade onto which the food stuff is placed. The netting is gathered exterior to the tubular element by a net gathering carry and the foodstuff is thereafter slid into the stuffing tubular element. The foodstuff is thereafter pushed out of the tubular element by a pneumatic system comprising a piston, and the gathered netting would be pulled over the food stuff. Thereafter the netting can be cut by cutting means and the food would be stuffed into the netting.

WO2016070883 discloses a system for packaging objects on a conveyor using a hose-shapedstretch foil. More specifically, WO2016070883 discloses a system, wherein the hoseshaped stretch foil can be wrapped around objects in a horizontal manner.

There is a need to improve the existing systems by reducing the size thereof and by decreasing the packaging time and complexity. In particular there is a need to improve the efficiency of packaging objects in hose-shaped enclosures.

SUMMARY OF THE INVENTION

The system according the present invention differs from the systems described above in that wrapping is achieved horizontally instead of vertically. Several technical features are essential to achieve horizontal wrapping and the system is characterized by a higher production cycle and hence a higher efficiency.

Thus, in a first aspect the present invention concerns a system for packaging objects with a tubular plastic film, said system comprises:

-   -   a movable gripping unit having a plurality of horizontally         oriented gripping arms for holding and releasing the tubular         plastic film onto an object;     -   a first conveyor for supporting the object and transporting it         toward the gripping unit in an axis parallel with the gripping         arms so that the object is delivered between the gripping arms;     -   a second conveyor for supporting the object and transporting it         away from the gripping unit, said second conveyor placed next to         the gripping unit, which during packaging is placed between the         first and second conveyors;     -   elements adapted for cooperating with each other for temporarily         holding the film, said elements enclosing a cutting device and a         welding device; and     -   a control unit.

The inventors have surprisingly found that when applying the elements adapted for cooperating with each other for holding the film encloses the welding and cutting device then several objects may be packaged in a row.

The elements adapted for cooperating with each other for holding the film preferably comprise a set of reciprocating elements that can be forced together in order to press against the outer surface of the film, while the cutting device and welding device, which is placed between the set of reciprocating elements, cuts and welds the film thereby generating two closed ends.

In a particularly preferred embodiment of the present invention the control unit is programmed to execute the following steps:

-   -   loading the movable gripping unit with tubular plastic film;     -   directing the movable gripping unit to be placed between the         first and second conveyors, whereby the gripping arms are         positioned axially with the conveyors;     -   activating the first conveyor to transport the object toward the         movable gripping unit, wherein the object moves along and in         between the gripping arms;     -   activating the gripping unit to release film from the gripping         arms onto the object while the object moves towards the second         conveyor;     -   set of reciprocating elements that can be forced together in         order to press against the outer surface of the film, while the         cutting device and welding device, which is placed between the         set of reciprocating elements, cuts and welds the film thereby         generating two closed ends; and     -   moving the object with closed ends to the second conveyor to         transport the packaged object away from the gripping unit.

In order to reduce the time for loading tubular film onto the gripping arms the movable gripping unit is preferably loaded with tubular plastic film for packaging at least 3 objects, more preferably for packaging at least 5 objects, and most preferably for packaging at least 10 objects.

In one embodiment the system is configured to accommodate a long object by consecutively releasing tubular film segments along the object, said segments overlapping each other along the length of the object.

The present invention also provides a method for packaging objects tubular film with the system of the present invention, said method comprises the steps of:

-   -   loading the movable gripping unit with tubular plastic film;     -   directing the movable gripping unit to be placed between the         first and second conveyors, whereby the gripping arms are         positioned axially with the conveyors;     -   activating the first conveyor to transport the object toward the         movable gripping unit, wherein the object moves along and in         between the gripping arms;     -   activating the gripping unit to release film from the gripping         arms onto the object while the object moves towards the second         conveyor;     -   set of reciprocating elements that can be forced together in         order to press against the outer surface of the film, while the         cutting device and welding device, which is placed between the         set of reciprocating elements, cuts and welds the film thereby         generating two closed ends; and     -   moving the object with closed ends to the second conveyor to         transport the packaged object away from the gripping unit.

The present invention also provides an apparatus comprising the set of reciprocating elements that can be forced together in order to press against the outer surface of the film, while the cutting device and welding device, which is placed between the set of reciprocating elements, cuts and welds the film thereby generating two closed ends. This apparatus is suitable for being implemented in both the system for packaging objects of the present invention as well as prior art packaging machines.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view of the elements adapted for cooperating with each other for temporarily holding the film, said elements enclosing a cutting device and a welding device.

FIG. 2 shows the packing of long objects.

FIG. 3 shows a prior art example of a system for packaging objects with a tubular plastic film.

DETAILED DESCRIPTION OF THE INVENTION

Identical components are given the same designations in the text which follows and are provided with the same reference signs in the drawings.

FIG. 1 shows a sectional view of the elements (10) adapted for cooperating with each other for temporarily holding the film (11), said elements (10) enclosing a cutting device (12) and a welding device (13). The steps carried out by the present invention includes the loading of the gripping unit (2) with tubular plastic film (11); directing the gripping unit (2) to be placed between the first (5) and second (6) conveyors, whereby the gripping arms (3) are positioned axially with the conveyors (5, 6); activating the first conveyor (5) to transport the object (7) toward the gripping unit (2), wherein the object (7) moves along and in between the gripping arms (3); activating the gripping unit (2) to release film (11) from the gripping arms (3) onto the object (7) while the object (7) moves towards the second conveyor (6); activating the set of reciprocating elements (10) thereby forcing them together in order to press against the outer surface of the film (11), while the cutting device (12) and welding device (13), which is placed between the set of reciprocating elements (10), cuts and welds the film (11) thereby generating one or two closed ends; and moving the object (7) with closed ends to the second conveyor (6) to transport the packaged object (7) away from the gripping unit (2).

FIG. 2 shows the packing of long objects. According to the invention it is achieved by configuring the gripping unit to accommodate a long object (7) by consecutively releasing two tubular film (11) segments along the object (7). Importantly these segments overlap with each other along the length of the object (7) and may be held in place by gluing or by a band, such as a strip.

FIG. 3 shows a prior art system (1), which is also applicable for performing the present invention. The system includes a movable packaging frame (2) having four horizontally oriented gripping arms (3) for holding and stretching tubular (stretchable) film (11). A rail system is used for moving the packaging frame from film storage and dispensing means (4) to the area between the first (5) and second (6) conveyors. In the shown embodiment two packaging frames and two film storage and dispensing means are provided; in such a configuration one of the packaging frames may be gathering stretch foil while the other is ungathering stretch foil onto the object to packaged. Each gripping arm is equipped with opposing and activated rollers which can be brought into contact with the film, whereby activation of the rollers enable the film to be gathered onto and ungathered from the gripping arms. The gripping arms are independently and laterally movable to achieve stretching of the film. There is shown a first conveyor for supporting the object and transporting it toward the packaging frame so that the object is delivered between the gripping arms. This first conveyor transports the object perpendicular to the packaging frame and in an axis parallel with the gripping arms.

The second conveyor, which is placed next to the packaging frame, supports the object and transports it away from the packaging frame. 

1. A system for packaging objects with a tubular plastic film, said system comprises: a gripping unit having a plurality of horizontally oriented gripping aims for holding the tubular plastic film and for releasing it onto an object; a first conveyor for supporting the object and transporting it toward the gripping unit in an axis parallel with the gripping arms so that the object is delivered between the gripping arms; a second conveyor for supporting the object and transporting it away from the gripping unit, said second conveyor placed next to the gripping unit, which during packaging is placed between the first and second conveyors; elements adapted for cooperating with each other for temporarily holding the film, said elements enclosing a cutting device and a welding device, said elements positioned at the end of the first conveyor; and a control unit.
 2. The system according to claim 1, wherein the elements adapted for cooperating with each other for holding the film comprise a set of reciprocating elements that can be forced together in order to press against the outer surface of the film, while the cutting device and welding device, which is placed between the set of reciprocating elements, cuts and welds the film thereby generating two closed ends.
 3. System The system according to claim, wherein an additional welding device is adopted between the elements adapted for cooperating with each other for holding the film, said welding device and said additional welding device flanking the cutting device.
 4. The system according to claim 1, wherein the control unit is programmed to execute the following steps: loading the gripping unit with tubular plastic film; ensuring that the gripping unit is placed between the first and second conveyors, whereby the gripping arms are positioned axially with the conveyors; activating the first conveyor to transport the object toward the gripping unit, wherein the object moves along and in between the gripping arms; activating the gripping unit to release film from the gripping arms onto the object while the object moves towards the second conveyor; activating the set of reciprocating elements thereby forcing them to press against the outer surface of the film, while the cutting device and welding device, which is placed between the set of reciprocating elements, cuts and welds the film thereby generating a closed end in the film covering the object; and moving the object with closed ends to the second conveyor to transport the packaged object away from the gripping unit.
 5. The system according to claim 1, wherein the gripping unit is loadable with tubular plastic film for packaging at least 3 objects.
 6. The system according to claim 1, wherein the gripping unit is movable.
 7. The system according to claim 6, wherein the gripping unit is movable, such as on a track, between a station for loading the gripping unit and the space between the first and second conveyors, where packaging of the object is performed.
 8. The system according to claim 1, wherein the system is configured to accommodate a long object by consecutively releasing two tubular film segments along the object, said segments overlapping each other along the length of the object.
 9. A method for packaging objects tubular film with the system of claim 1, said method comprises the steps of: loading the gripping unit with tubular plastic film; directing the gripping unit to be placed between the first and second conveyors, whereby the gripping aims are positioned axially with the conveyors; activating the first conveyor to transport the object toward the gripping unit, wherein the object moves along and in between the gripping arms; activating the gripping unit to release film from the gripping arms onto the object while the object moves towards the second conveyor; activating the set of reciprocating elements thereby forcing them together in order to press against the outer surface of the film, while the cutting device and welding device, which is placed between the set of reciprocating elements, cuts and welds the film thereby generating one or two closed ends; and moving the object with closed ends to the second conveyor to transport the packaged object away from the gripping unit.
 10. The method according to claim 9, wherein the gripping unit is configured to accommodate a long object by consecutively releasing two tubular film segments along the object, said segments overlapping each other along the length of the object.
 11. The method of claim 10, wherein the overlapping segments are held in place by gluing or by a band, such as a strip.
 12. An apparatus for holding a tubular film while said film is being welded an cut, said apparatus comprising elements adapted for cooperating with each other for temporarily holding the film, said elements enclosing a cutting device and a welding device.
 13. The apparatus according to claim 12, wherein the elements adapted for cooperating with each other for holding the film comprise a set of reciprocating elements that can be forced together in order to press against the outer surface of the film, while the cutting device and welding device, which is placed between the set of reciprocating elements, cuts and welds the film thereby generating two closed ends.
 14. The apparatus according to claim 12, wherein the apparatus comprises an additional welding device placed between the elements adapted for cooperating with each other for holding the film, said welding device and said additional welding device flanking the cutting device. 